Pilot igniter for burners



Feb. 27, 1962 s. A. MocoLLUM PILOT IGNITER FOR BURNERS 2 Sheets-Sheet 1 Filed April 29, 1948 INVENTOR STERLING A. MGGLLUH ATTORNEY Feb. 27, 1962 s. A. MCCOLLUM PILOT IGNITER FOR BURNERS 2 w u HMM mwa m www lm .2 2 M/ Filed April 29, 1948 ATTORNEY United rates arent dige Zg Patented Feb. 2?, 1962 3,022,630 PROT IGNETER FSR BURNERS Sterling A. McCollum, Laramie, Wyo., assigner to the United States of America as represented by the Secretary of the Navy Filed Apr. 29, 1948, Ser. No. 24,922 4 Claims. (Ci. 6G-39.82)

rfhe present invention relates to burners, more particularly to an improved pilot igniter for a burner, which is speciiically intended for use in the combustion charnber of a ram jet motor, whereby blowing out of the ame is prevented, thus to insure uninterrupted combustion.

in ram-jet-propelled projectiles, fuel in liquid form is injected into and mixed with air passing through a central duct or combustion chamber and, after thorough mixing, the resulting mixture is ignited and burned to supply the propulsive force. Burning cannot be maintained at the rates of air ilow encountered in practice without the use of some sort of pilot igniter to continuously sustain ignition, and a means for reducing the velocity of the air and fuel mixture. Accordingly, the principal obiect of the present invention is to provide a pilot igniter having a sheltered area in which the mixture velocity is low enough to permit continuous burning of a plurality or" pilot flames for continuous ignition of the miX- ture flowing through and around the igniter.

A further object of the present invention is to provide a pilot igniter having a plurality of sheltered pilot llames distributed across the cross-sectional area of a combustion chamber.

A still further object of the present invention is to provide a pilot igniter which will produce the necessary shelltered conditions for the maintenance of the pilot flames.

Another object of the invention is to provide the combination of a burner chamber wall and an igniter occupying a place in said chamber, said igniter being so supported as to define a sheltered pilot flame burning area adjacent its downstream end and directly in the combustion stream.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. l is an axial section of a form of the device showing a fragment of the combustion chamber of a ramjet containing the igniter proper and some of the associated piping, and embodying the present invention;

FIG. 2 is a view in elevation of the igniter shown in FIG. i; and

FIG. 3 is an isometric view partly in axial section of another form of the device installed in a ram-jet combustion chamber and having two concentric pilot-igniter units.

Referring now to FIGS. 1 and 2 the igniter assembly comprises a fuel manifold which consists of an annular or ring element having a V-shaped or similarly indented annular groove 12 in its downstream or front end defined by faces in diverging relationship, and two concentric annular grooves 14 and 16 in its upstream end, formed by the outer and inner walls of the ring element and a separating annular iin 18. Two rings 20 and 22 are tted on a portion of the partition, being applied over the open upstream ends of the grooves 14 and 16 to convert said grooves into outer and inner annular chambers, which rings are so shaped as to provide a smooth, doubly convexly or toroidally curved upstream surface on the burner. These chambers communicate with the V-shapcd groove 12 by means of sets of paired orifices 24 and 26 through the diverging downstream faces to which said oriices are normal, although oriented in the general direction of the combustible mixture stream. The orifices therefore converge, causing the iluids jetting from each pair to mutually impinge upon each other in the sheltered zone backed by the V-shaped groove 12. The element 10 thus constitutes a pilot arne jet ring at which the ames are sustained in the combustible stream, insuring uninterrupted cornbustion of the mixture. Access to the annular Chambers is provided Vby entrance ports 28 and 36 in the rings 26 and 22. Rectangular inlet fittings 32 and 34 having 1ongitudinally disposed bores 36 and 3B, respectively, are at tached to the burner assembly in such positions that said bores communicate with the ports 28 and 30, respectively. Said bores intersect lateral bores 4t) and 42 which are threaded to receive inlet pipes 44 and 46.

In operation, fuel, such as acetylene, admitted through the pipe 44, passes therefrom through the bore 36 and the port Z8 into the inner chamber 16 and from there emerges through the orifices 24 into the annular V-shaped groove 12. Similarly, a combustion-supporting uid, such as air, or preferably oxygen admitted through the pipe 46 passes through the bore 3S and the port 30 into the outer annular chamber 14, said respective gases emerging therefrom through the orifices 24, 26. The jets of fuel and oxygen emerging from the orices 24 and 26, respectively, merge to form a combustible mixture which, when ignited, produces a ring of pilot flames 48.

it will be obvious that while the best results as to a hot, persistent pilot flame are secured by using substantially undiluted oxygen as the combustion-supporting fluid, in some instances this may not be necessary, and even considerably diluted oxygen, such as air, may serve adequately. The term oxygen as used in this case is therefore to be understood t0 include substantially pure oxygen as well as other combustion-supporting uids.

The air-fuel mixture to be ignited flows through the combustion chamber 49 in which the pilot igniter assembly is installed in the direction shown by the arrow, is ignited by the llames 48, and will burn as long as the flames continue.- tuds 49a of which there is a plurality, extend from the igniter. Screws 49h of which there is an equal plurality, are driven through the wall of the combustion chamber, in which wall the screws are adjustable to center the assembly.

Referring now to FIG. 3 the modified form of assembly shown consists essentially of two concentric pilot igniters as described above. These igniters are supported in a duct or combustion chamber 52 by means of studs attached to the igniter and screws passing through the wall of the duct and engaging the outer ends of the studs. In the embodiment shown, the outer igniter 54 is supported by studs 56, one of which is shown in section at 56a attached directly thereto and screws 58a through the duct wall engaging the studs, and has attached to it inlet iittings 32a and 34a and pipes 44a and 46a. The inner igniter 6G has an extension attached thereto consisting of a solid ring 62 provided with bores 64 and 66 communieating with the ports 28h and 39h in the burner proper. Said extension ring has attached to it inlet ttings 32h and 34b, pipes 44h and 4Gb and supporting studs 56b, and is held in place by screws 58b. This construction is necessary to provide clearance for the studs past the outer igniter.

Operation of the igniter in FIG. 3 is identical with that previously described except that the assembly of FIG. 3 provides two concentric sets of pilot dames.

Obviously many modications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is: Y l. In a burner, a pilot igniter mounted in the ow path of the combustible mixture of the burner and having a .ring-shaped fuel manifold, a similar oxygen manifold concentric therewith, and fuel and oxygen supply pipes connected to Ithe respective manifolds, said manifolds having paired, converging orifices through the downstream faces thereof providing mutually impinging .jets of fuel and` oxygen ignitable to form a ring of pilot ames. 2. In `a burner, aV pilot igniter mounted the flow path of the combustible mixture of the burner and having a Vring-strapped fuel manifold, a similar oxygen manifold concentric therewith, and fuel'and oxygen supply pipes connected to the respective manifolds, said manifolds having `end faces in downstream diverging relationship, said faces having paired orifices normal thereto and therefore converging toward each other to provide impinging jets of fuel and oxygen ignitable to form a ring of pilot flames. Y

3. A pilot burner for a fuel burner comprising a fuel manifold which consists of a ring element havingrouter and inner walls connected by a front end which has faces diverging in the fuel downstream direction, said faces having orices normal thereto so as to provide Yconverging fluid jets, a partition extending back from the end,

rings -tted on a portion of `the partition and against'theV end two concentric annular Huid-supply channels, there being a set of paired converging passages each communieating at one end with the corresponding one of said channels and opening at its other end through the adjacent face of the groove, whereby combustible fluid and combustion-supporting fluid may be deliveredinto said groove from the respective channels.

References cited in the fue f this paient UNITED `STATES PATENTS 1,932,321' Moseley 7.1. Oct. 24, 1933 2,180,789 Browning Y Nov. 21, 1939 2,395,114 Goddard r Feb. 19, 1946 2,416,389 Heppner etal Feb. 25, 19747 2,417,445 Pinkel Mar. 18, 1947V FOREIGN PATENTS France Ian. 8, 1947 

